Biogeochemical controls on the structure and functioning of arctic terrestrial ecosystems

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The overall goal of my proposed research is to substantially advance our understanding of how arctic tundra ecosystems function. As an ecosystem ecologist, I study how plants interact with animals, with the soil and soil microbes, as well as with the atmosphere in ways that significantly influence biogeochemical cycling and therefore ecosystem functioning. The context for this approach is that understanding the functioning of the system is necessary to be able to predict its responses to perturbations such as climate change. Over the next five years, I will have 3 main research objectives: a) To determine the extent and ecological significance of our lab's recent study indicating that mesic tundra plant growth may be as limited by the availability of phosphorus, as by nitrogen. This result challenges the fundamental and widespread assumption that tundra plant growth is primarily limited by nitrogen, and has critically important implications to understanding and predicting how these ecosystems may respond to climate change because the two elements have fundamentally different biogeochemical cycles. b) To further develop an integrated landscape and regional-scale conceptual framework with which to understand and predict patterns of increased shrub growth and expansion in the low Arctic. c) To characterize and compare spatial patterns of fungal community composition and controls on their distribution with those of bacteria, and to better understand their relative importance in key biogeochemical processes that will likely be affected by climate change. The proposed studies involve intensive experiments in N.W.T. as well as regional sampling, and will lead to significant new insights that will further improve our ability to understand how arctic terrestrial ecosystems function as well as providing substantial cutting edge scientific training opportunities. Ultimately, I hope that this research will lead to better land management in the North, as well as greater public appreciation of the ecological value of the Arctic, and therefore to more effective environmental policies and practices for Canada.